Is A76 And 76a The Same Battery

0 views

Skip to first unread message

Cecile Lilien

unread,

Aug 3, 2024, 5:57:42 PM8/3/24

to couprocheckthron

I am building a quadrocopter with four 6V DC motors and an arduino nano. I have the motors running beautifully using four AA batteries (2 parallel and 2 in series to provide 6V with NPN transistors and diodes to protect the nano), but obviously I will need a much smaller battery pack to get it up in the air. I was using the AA's just for testing purposes while I learned how to control the motors from the arduino.

I have two 3.6V batteries that would be perfect for this purpose. If I wired them in series so that the voltage is 7.2V, and then cut down the voltage to 6V using resistors, I believe I could power the motors with them just fine. But how can I possibly supply the nano with power using the same batteries? Trying to supply 4 motors and the nano, which have different voltages, is confusing to me. Can anyone please point me to a good resource that would help with this question?

A voltage regulator is not enough in this case. Motors inject a lot of electrical noise into circuitry and without proper power supply decoupling (noise filters) you are guaranteed to have problems. This is not a good problem for a beginner to tackle.

jremington:
A voltage regulator is not enough in this case. Motors inject a lot of electrical noise into circuitry and without proper power supply decoupling (noise filters) you are guaranteed to have problems. This is not a good problem for a beginner to tackle.

I am using diodes to ensure that voltage doesn't travel in the wrong direction. It seems to be working just fine, I have not had any issues with the motors. Using diodes seems to be a very common solution to this problem. Are you sure that it's not enough?

I am a beginner but I am a quick learner. Or at least I like to think that I am lol. I have already got the motors working though, I can control their speed using a custom PWM system and they're working perfectly.

Using diodes is a very common bandaid, not a general solution. Diodes do not protect from positive overvoltage spikes. However, the problem depends on the motors and such an approach could work in your case.

jremington:
Using diodes is a very common bandaid, not a general solution. Diodes do not protect from positive overvoltage spikes. However, the problem depends on the motors and such an approach could work in your case.

Thanks very much for your response. In regards to powering the arduino and the 4x 6V DC motors off of the same 7.2V battery, do you have any thoughts? The battery would be composed of two high capacity LiPo 3.6V batteries wired in parallel to produce 7.2V.

For simple brushed DC motors, it helps a lot to use 3x0.1 uF capacitors. One goes directly across the motor terminals and the other two from each terminal to the motor casing. This tutorial from Pololu shows you how: Pololu - 9. Dealing with Motor Noise

Just a question, if you wire the motors together in a series, how can you use transistors to selectively increase and decrease power to each individual motor? For a quadrocopter it is a requirement in order to make it able to move in the X Y plane and rotate.

I have wired the two batteries in series to produce 7.2V. I ended up buying an adjustable voltage regulator (LM317T) and it is producing a consistent 5.05V. I have it powering the Arduino just fine. I have the motors hooked up to the battery in parallel with the Arduino (before the LM317). My motors say 6V but they run on 7.2V without problems, I will be careful not to run them for too long. I am using a diode to protect the Arduino.

PS - for anyone attempting this in the future, it is best to put a 100F electrolytic capacitor between the 5V regulator and the arduino VIN. In my case, the battery provides plenty of current between the motors and the arduino but there is a lot of "noise" causing issues. As previous posters in this thread have said, it smooths out a lot of the bumps.

Hey, I faced the same issue. The solution, like others have mentioned in the forum is to use decoupling capacitors. The motors take up too much current initially, and the Arduino keeps resetting itself. I added 2x 1uf capacitors across Vin and ground, and it worked! . Start with small value of capacitors like 1nf and keep increasing.

I have several APC UPS units protecting a variety of servers and workstations I'm in charge of. I've discovered over the years that many use the same battery but claim to have a different output power capacity and was hoping someone could give me clarification as to why. For example - the BE650G and BE750G take the exact same battery but claim 390/450 output watts respectively. I always thought of a battery as having X amount of stored power to release and can only theorize that the higher end UPS units are more efficient at converting the stored energy to 110 vac but would appreciate an accurate answer. Thanks.

Yeah, it's a little unusual that a higher power UPS is more efficient. Usually they are less efficient due to larger components or more components, but it's certainly possible the designers went with a more efficient design to get more power.

The two different UPSs which use the same spec battery run time may vary at different power loads. The Same battery does not mean that the these units should provide the same run time at 100 Watts of load because these units output power capacity is not same.

Then I guess a followup question would be - If the exact same load were drawn from the UPS units which use the same battery and are output rated at 650/750 or 390w/450w, would you expect them to have pretty much the same runtime?

The BE750G and BE650G UPSs runtime is 7 mins if the connected equipment consumes 300 Watts. Click on the below link to compare these units runtime.
_for_extendedruntime.cfm?upsfamily=21

The BE650G supports up to 390 Watts / 650 VA, where as the BE750G supports up to 450 Watts / 750 VA on the battery backup outlets. So if the connected equipment exceeds the UPS rated capacity, it will be overloaded. Therefore, I would size a UPS which meets my requirements(Runtime, Output power, etc.,) in order to protect the equipment from Power Problems.

I'm not disputing your advice to get a UPS that meets the need, I'm just trying to understand why different runtime claims are made for different UPS units that use the exact same battery. Yes, the BE750G and BE650G show the same runtime of 7 mins if the connected equipment consumes 300 Watts but why with a 100 watt load will the BE750G run for 38 mins vs the 32 for the BE650G? Same battery, same stored energy...

My new Canon 90D is powered by LP-E6N battery. Dimensions are the same as LP-E6 batteries, just the mAh is little higher. Experts opined that both these batteries can be used interchangeably. So, I decided to put this to test. LP-E6 packs 1800mAh and LP-E6N features1865mAh.

Total battery capacity is just part of the specification picture, another aspect is how much current it can produce under load and with how much voltage drop. Your 90D is likely basing the "change battery" recommendation on the voltage delta between no load and loaded.

This same issue shows up in other ways. My first Canon 1 series was a 1D Mark II and at one point I needed replacement battery packs in a hurry before heading on a trip. B&H and Adorama were both back order status on Canon so I tried a third party brand. It seemed to charge and work normally UNTIL I shot a few fast bursts with the 1D M2 and I noticed the battery level indicator would drop from full to 1/4 during the burst and if I didn't immediately interrupt the burst then the camera would lock up requiring battery removal to reset. After a burst, the indicator would return to indicate a fully charged pack. The third party pack just couldn't sustain the 1 series burst current demand causing voltage to sag under that load.

Your experience sounds frustrating, but I've got a similar story. When I upgraded my camera, I faced a similar dilemma with battery compatibility. Turns out, even slight differences in mAh can affect performance. It's weird how finicky electronics can be sometimes!

Run a battery cable sized wire to a 12v fuse box, and at the fuse box, Y it off to the inverter. I would also add an appropriately sized fuse or circuit breaker between the battery & the fuse box, and between the fuse box and the inverter.

The positive battery cable connects to the large screw on the bottom, the positive cables of each DC appliance connect to one of the six screws on the bottom, and then their negative cables connect to one of the six screws on top, which are the negative bus bar (I think), and the power then flows back to the battery through a negative cable which is attached to the large screw at the top. Is this correct?

At the bottom of your fuse box diagram, there appears to be a large stud at the bottom center for power going into the fuse box, and it says to put a fuse in that line of a max of 125 amps. So your cable should be sized to carry 130+ amps @ 12 vdc and it should connect to the stud with a ring terminal.

So if the positive cable going to my inverter is a 130 amp cable that connects to the stud at the bottom of the fusebox, should the negative cable going to my inverter also connect to the fusebox at the stud on top?

If your house battery is grounded to the chassis, then the inverter can be grounded to the chassis as well to save a longer cable run. If not, then yes connect it to the negative on the fuse box. The negative cable should be the same size as the positive cable.

Find the specs for your alternator, then add 10-25% for the isolator size. You always want the cables & equipment to be over rated for the maximum possible going through them. This helps eliminate problems down the line.